Liquid rheostat.



D. WELGE.

LIQUID RHEOSTAT. APPLICATION FILED 050.16. 1914.

1,157,134. Patented oet. 19, 1915.

A: 5 A: WJ'TNE55E5. f JNVE'NTH @05W Wi/@7% UNITED STATES PATENT OFFICE.

DIDRIK WELGE, or SOUTH roRcUPINE, ONTARIO, CANADA.

LIQUID RHEos'rAT.

Specification of Letters Patent.

Patented Oct. 19, 191:5.

Application led December 16, 1914. Serial No. 877,564.

To all whom it may concern Be it known that I, DIDRIK WELGE, a subject of the King of Norway, residing in the town of South Porcupine, in the District of Temiskaming, Province of Ontario, Canada, have invented certain new and useful Improvements in Liquid Rheostats, of which the following is a specification.

This invention relates to liquid rheostats especially adapted for use with three-phase induction motors. Such rheostats have usually been made either of the one tank or,A

the three tank type. With the three tank type much difliculty is eXperiencedin keeping the density and the level of the liquid the same in each tank. In lthe single tankl the same length are formed in the liquid bey tween each of the blades and the others. This result is best attained by forming each blade in plan as an obtuse angled V, and by arranging each blade so that its halves are substantially equally spaced respectively from one half of each of the other two blades.

The eliciency of the rheostat may also be increased by placing a three-bladed neutral plate between the three live blades, the parts of the neutral plate being in electrical connection, substantially as hereinafter more specifically described and illustrated in the accompanying drawings in whicho Figure 1 is an elevation showing my invention in its simplest arrangement as connected with a three-phase slip-ring induction motor; Fig.'2 a perspective detail showing the live blades as arranged without a neutral plate; Fig. 3 a similar view show.- ing a neutral plate arranged in use with the live blades; Fig. 4: a sectional view on an enlarged scale showing the method of connecting the live blades; and Fig. 5 a similar view showing the connection employed when a neutral plate is employed with the live blades.

In the draw-ings like numerals of reference indicate corresponding parts in the different figures. Y.

Referring particularly to Fig. 1, 1 is a conventional representation of a slip ring rotary induction motor. 3 are the live blades of the rheostat, to which the connections are secured. Each blade is provided with a suitable terminal such as the rod 4 with which connections may be made. 5 is the tank containing the liquid.

Any of the ordinary arrangements may be used for causing the immersion of the blades in the liquid. A simple form is shown in Fig. 1,.viz. a 'cable secured vto the blades and passing over la pulley 6 suitably supported `overhead and adapted to be made fast in any suitable manner. v

The blades are shaped and-arranged as shown more particularly in the detailed views. The blades are three in number, and

each blade in plan, it will be seen, is of a V. shape, the angle between the halves being an obtuse angle of approximately 120 degrees. These blades are brought into juxtaposition so that the halves of each blade are substantially equally spaced respectively from one half of each of the two "other blades. It is preferable, though not essential, that cross sections ofthe halves of the blades should be parallel to the cross sections of the halves4 of the adjacent blades. Usually the blades will also be arranged so that vertical sections of each half of each blade will be parallel to the corresponding sections of .adjacent blades, though this arrangement 1s not essential. e

The essential feature ofthe arrangement is that the "paths through the liquid in the tank should be of equal resistance between each blade and each of the others, so that the rotor circuit of the motor with which the device is employed will be equally balanced.

The lower edges of the blades will have the tapered configuration Shown in order that there shall be a very gradual increase of the submerged area of the blades, .but this arrangement is, of course, old in the art and. no particular claim is made to it.

The arrangement shown in Fig. 2 is very eii'icient, but still greater eficiency is` obtained by the Aemployment of the three bladed neutral plate 7, which is supported between the live blades, but is not electrically connected with any of them. Without the use of this neutral plate, only one half of the immersed area of the blades at any given period is active, whereas when the neutral plate is employed it forms a path whereby current can flow from one blade to a position from which it can flow to parts of the surfaces of the other blades, which lwithout the neutral plate would be sepa'- insulating material and 10 two knobs of insulating material. The knobs are adapted to fit within the sleeve as shown, the blades 3 lying between their heads and the ends of the sleeve 9. When the bolt 8 is tighte d up, the plates are suitably held in fixed relationship to one another and are completely insulated from one another. When a neutral plate is employed `two sleeves 9 must be used, the'neutral plate lying between the ends of the two sleeves. The knobs 10 are preferably so proportioned as to extend from end to end of the sleeves.

From the above descri tion it will be seen that I have devised a orm of blade construction for liquid rheostats which will effectively attain the objects of my invention as set out in the preamble of this specication. v

What I claim as my invention is 1. A liquid rheostat of the single tank type provided with three live blades, each V-shaped in plan, said blades being arranged so that the halves of each blade are substantially equally spaced respectively from one half of each of the two other blades.

2. A liquid rheostat of the single tank type provided with three live blades, each V- shaped in plan, said blades being arranged so that the halves of each blade are substantially equally spaced respectively from one half of each of the two other blades; and a three-bladed neutral plate set between the live blades and having its parts equally spaced therefrom.

3. A liquid rheostat of the single tank type provided with three live blades, said blades being shaped and arranged to form in the liquid 0f the tank paths of equal resistance between each blade and each of the others.

4. A liquid rheostat of the single tank type provided with three live blades, said blades being shaped and ,arranged to form in the liquid of the tank paths of equal resistance between each blade and each of the others; land a three-bladed neutral plate set between the live blades and equally spaced therefrom.

Signed at South Porcupine this 2 lday of December, 1914, in the presence of the two undersigned witnesses.

' DIDRiK WELGE. [1.. 5.] 

